Electrode



M. F. MILLER April 26, 1949.

ELECTRODE Filed May 22, 1945 IN V EN TOR.

Maurice fl/WY/er BY 47'7ORNEY Patented Apr. 26, 1949 UNITED STATES PATENT OFFICE My invention relates to electrodes for gaseous discharge tubes and particularly but not exclusively to tubes of the cold cathode type. More particularly, it refers to a preformed electrode assembly which is adapted to be fused to the ends of the tube partially to seal the same, and which is provided with means facilitating the exhausting and final complete sealing of the tube.

One the objects of my invention is to provide an electrode for a lamp or tube of the fluorescent type which will permit the use of practically the full length of the tube for light and thus eliminate the dark spaces which now exist in continuous lighting strips. Another object is to provide an electrode of such type that substantially the entire surface area of one side thereof is exposed to the gas column in the tube whereby the emission is increased. Another object is to provide an electrode which is extremely short, which has good insulating characteristics and which is adapted for application to either end of the tube. A further object is to provide a preformed electrode of simple, stable construction which may be readily fused to the ends of the tube to position the electrode therein and incidentally to seal the tube.

I attain these objects by means of the novel elements and the combinations and arrangements thereof described below and illustrated in the accompanying drawing in which- Fig. 1 is a fragmentary, exploded, longitudinal section through a gaseous discharge tube including my electrodes at the end thereof; and

Fig. 2 is a sectional view of a short piece of glass tubing illustrating how my electrode is formed therefrom.

Referring to the drawing My electrode comprises an element I which may formed from a short length of glass tubing by outwardly flaring one end 3 of the tube, as shown at 3, and forcing the other end 4 of the tube inwardly, as shown at 4 to seal the same with the wires 5 and 6 extending therethrough. The marginal portions 1 of the element l are flat and the periphery is circular and of a diameter somewhat in excess of the inside diameter of the tube to which the electrode is to be applied so that it may serve as a cap for the end of the tube and may be easily fused thereto to seal the tube.

Secured to the glass element I is a metallic cup 8 which is formed with a deep re-entrant bottom 9. Spaced holes are provided in the re-entrant .portion through which pass the wires 5 and 6 which are bent over and welded to the inside of the bottom of the cup as shown at I0. Between the glass element 1 and the cup 8, and within the re-entrant portion of the bottom of the cup, I preferably position a mica disk I I which serves to maintain the metal cup in stable, spaced relation to the element l. The diameter of the cup is somewhat less than the inside diameter of the lamp tube 12, preferably about A" less, so that the side wall of the cup is spaced from the inside wall of the tube. The interior of the cup is provided with an emission coating I 3 and it is to be understood that the inside of the lamp tube 12 is also provided with a fluorescent coating, not shown.

Since air must be exhausted from the inside of the lamp tube after the electrodes have been fused thereto a short, glass tube H has one end thereof fused into one of the elements I, and a transverse passage l5 communicating with the interior of the tube I4 is blown through one side of the element I. Thus, after the electrodes have been fused to the lamp tube the tube may be exhausted by pumping out the air through the tube M which may then be out off and sealed as shown I From the foregoing it will be apparent that by forming the cup 8 with a deeply re-entrant bottom I have not only substantially increased the emission area of the inside of the cup but I am thus enabled to position the bottom of the cup quite close to the plane of the rim thereof so that it is directly exposed to the gas column in the lamp.

Although the interior of the cup has a comparatively large area it is quite short or shallow and thus I am able to use practically the full length of the lamp tube for illumination. Long dark spaces between lamps used in continuous lighting strips are thus eliminated and the efficiency of the lamps is substantially increased.

What I claim is:

1. As a new article of manufacture, a preformed electrode for a gaseous discharge .tube comprising a, metal cup of substantially greater diameter than height adapted to be inserted in said tube in spaced relation to the wall thereof, a glass disk of greater. diameter than said cup coaxial with said cup and adapted to be fused to the end of said tube to seal the same, a refractory disk between said cup and said glass disk and spacing the same, and current conducting means extending through said disks and secured to said cup for holding the whole together.

I 2. As a new article of manufacture, a preformed electrode for a gaseous discharge tube 3 comprising a cylindrical metal cup of greater diameter than height; the central portion of the bottom of said cup extending upwardly to a zone substantially nearer the top of said cup than does the outer portion of the bottom of said cup, a glass disk adapted to be fused to said tube to seal the same and having its central portion approximately complementary to the outside configuration of the bottom of said cup, a refractory disk between said cup and said glass disk and maintaining the two in spaced, partially nested relation, and current conducting means secured to said cup 'and extending through said disks in hermetically sealed relation to said glass disk and holding-the whole in assembled relation.

, MAURICE F. MILLER.

REFERENCES crran file of this patent:

Number 15 Number UNITED STATES PATENTS Name Date Moore May 17, 1910 Kenty Feb. 14, 1933 Bymes Feb. 21, 1933 Ende- July 18, 1935 Miller Dec. 15, 1936 Boucher- May 10, 1939 Breadner et al. June 13, 1939 Miller Apr. 15, 1941 Hunt Sept. 2, 1941 FOREIGN PATENTS Country Date Australia July 5, 1935 The following references are of record in the 

